Do negotiate face to face with the decision maker is what I learned from my HR.
I did a successfull face to face negotiation after I left Physics and found the first IT job.
I also did successfull negotiation by phone from Texa with VP in California.
And I did several more negoation on the phone in California in these years.
I prefer talk either face to face or by phone.
Some friends use email, also get good raise. Good sample emails are: 小魚兒, 草酶派, Steven's Mom, etc. I archived these 黃金 emails in my website, you can get them.
最終, 隻要掌握談判的精華, 用啥方法都中.